What fuel

[sinclairsinclair]

No pants, that might chafe a bit???

[MadMaxHSV]

MadMaxHSV said:

ringram said:

I run mine on 95 the manual says its best on 98, but I get hardly any/no knock (logged hours of driving)
The vxr8 307kw seems to run about 2deg more timing than the 297KW LS2 in the monaro (In fact that may be the main power difference, Piers is doing some testing on this)

Aiming to flash the timing map and log some runs tomorrow, will report back.

Re-flashed this morning, and running without issue.
I'm using Shell V-Power for a variety of reasons and the added timing of the VXR8 map should help it make better use of the octane rating. Difficult to judge but the car seems to pull better with greater response in the mid-range with smooth delivery to the redline. Hard to tell though without a dyno to backup.
There was no audible knock anywhere, but to be honest wasn't expecting any with the fuel and still running a 'factory' tune. Will be doing some logging to ensure no knock is present. If Richard has run 95 in his VXR8 with no issues I reckon even more timing could be added to get best performance running 98 or higher.

[ringram]

Possible yes. But you wont know unless its measured on the dyno like you say.
Max possible timing without knock does not equal more power. Minimum best timing does... There is a difference.

[MadMaxHSV]

True, there is the point that torque drops off after MBT. I'll stick to this for now. Also would depend on the fuelling. As you've said as stock they run fairly rich which would allow more timing....
Still haven't changed the PE tables yet but will be onto that shortly.

[Paul--C]

ads_green said:

PS - don't bother with fuel additives.
Any super unleaded from any supplier is going to be blended with lots of additives so I would be very careful using any octane booters.

I beg to differ......I use Millers CVL in all my cars and have done for years, one bottle with every 20 litres. The improvement in fuel economy means it pays for itself plus you can honestly feel the performance improvement. CVL is an Octane Booster and apparently the only FIA approved one out of interest. http://www.millersoils.net/1_Millers_frame_MOTORSP...

[stevieturbo]

ads_green said:

stevieturbo said:

The higher the CR, and softer the engine, then definately use the best petrol you can get...

I made my 850 at the hubs, on regular 97 SUL.

Forced induction does make things more complicated - most FI engines run a reduced cylinder compression ratio to account for the air charge being under positive pressure rather than pulled in. You can pretty much get this ok with a non intercooled setup as the results are easier to reproduce for accurate mapping. However throw in an intercooler than it becomes incredibly difficult to get a decent map working in all situations as the effect on the air charge is so variable given the different operating conditions.

Charge air temp sensor. I dont see what is incredibly difficult about forced induction tuning.

Perhaps difficult to tune at the ragged edge. Even I wouldnt be bothered with that...and definately not with a customers car.
I dont even take those risks with my own anymore.

[ads_green]

stevieturbo said:

ads_green said:

stevieturbo said:

The higher the CR, and softer the engine, then definately use the best petrol you can get...

I made my 850 at the hubs, on regular 97 SUL.

Forced induction does make things more complicated - most FI engines run a reduced cylinder compression ratio to account for the air charge being under positive pressure rather than pulled in. You can pretty much get this ok with a non intercooled setup as the results are easier to reproduce for accurate mapping. However throw in an intercooler than it becomes incredibly difficult to get a decent map working in all situations as the effect on the air charge is so variable given the different operating conditions.

Charge air temp sensor. I dont see what is incredibly difficult about forced induction tuning.

Perhaps difficult to tune at the ragged edge. Even I wouldnt be bothered with that...and definately not with a customers car.
I dont even take those risks with my own anymore.

FI makes the comparison of RON/MON a bit more complicated as they are measured using a NA engine.

It's not so much FI that is difficult - but intercooling gives alot of challenges. The charge air temp sensor gives you the temp but I was meaining more the compliexity of the map to use it. You still have to apply a map for the different charge temp ranges and an intercooler makes this parameter considerably more variable.

[Black VXR]

The main thing is to use 'fresh' fuel. Petrol goes off quickly and 98 fuel even quicker than standard fuel. Buy from a high turnover outlet and if you leave you car for weeks on end with 'good' fuel in the tank it will have gone off and lost some of its properties.

[Gas_Man]

Another reason why I use Tesco 99... it never sits around for long at the supermarket. In fact they've been known to run out more than once.

[ads_green]

agreed - it used to be recommended that when leaving/storing a car that the fuel tank be topped to the brim in order to prevent fuel tank corrosion.

Most (if not all) modern cars have fuel tanks that are either aluminium or corrosion resistant steel so this isn't a problem any more